For Pistons(R44 and R22) we teach - 53kts S+L over the site carb cold. Compare your MAP to your 5min rating. If you have 6"(R22) or 8"(R44) spare your have power to spare and can hover OGE. Wouldn't recommend going into a confined area with less. For departure, 2ft IGE hover and compare MAP with 5min rating, if more than 2" it will lift vertically. 1 1/2" and you could get away with a towering. Remember to actually pull your 5min rating(before approaching) at some point to make sure you can attain that power without rotor droop.